I definitely agree with this phenomenon. Right now I feel like I have gained two very exiting things at the same time: a relationship with my girlfriend and a new shade to my relationship with my husband. The latter has more to do with opening up to poly than with my relationship with my girlfriend, I think. Therefore, it would still be a permanent change in my marriage even if my other relationship was to end.
We have had so many interesting conversations and much openness with my husband, and I feel a new kind of connection between us. He says he feels more attracted to me since I am apparently cute when I have a crush.
I wouldn't describe this as NRE, it is not as intense (which I don't mind since NRE is quite tiring). But there are similar aspects, we have spent a bit more time together recently and we do have more sex as well.